Experimental Study of Structure–Energy Changes in Molecules and Crystals of 2,2-Dinitropropane-1,3-diol Caused by Temperature Variations

Temperature-Dependent Structure–Energy Changes in Crystals of Compounds with Poly(hydroxymethyl) Grouping

“…The structure of tris(hydroxymethyl)nitromethane (1) and tris(hydroxymethyl)aminomethane (2) was studied at room temperature. The reflection intensities were measured in the range 0.02 sin y/l 0.50 on a four-circle KM-4 (KUMA-Diffraction, Poland) diffractometer with the o=2y scanning technique.…”

“…Tris(hydroxymethyl)aminomethane crystals 2 were examined with the same instrument in the range 293-467 K. The thermogram showed three peaks: the first, at T KI (2) = 352 K with a very small thermal effect, the second at T KII (2) = 409 K with DQ II (2) = À10 kcal/mol, and the third one at T KIII (2) = 433 K with DQ III (2) = À1 kcal/mol. Except for the very small third peak after the phase transition at T KII (2) no thermal anomalies were found up to 467 K. It was probable that the third peak was connected to the melting, the thermal effect of which was 10 times smaller than DQ II (2) .…”

“…A complex study of structure-energy changes both in separate molecules and in a crystal lattice as a whole for the compounds RNO 2 C(CH 2 OH) 2 , where R = Br, NO 2 , was carried out in our earlier work [1][2][3]. It has been shown that conformational changes in the molecules during temperature elevation begin from torsional oscillations in the most energy-consuming fragments, nitro groups, and are accompanied by the redistribution of structure, forming hydrogen bonds.…”

“…The crystals 1 for investigation were grown from a mixture of isopropyl alcohol and chloroform. Tris(hydroxymethyl) aminomethane (2) and the crystals (2) were grown from ethanol solution.…”